Using hydrodynamic simulations and a technique to extract the rotational
component of the velocity field, we show how bubbles of relativistic gas
inflated by AGN jets in galaxy clusters act as a catalyst, transforming
the energy carried by sound and shock waves into heat. The energy is
stored in a vortex field around the bubbles, which can subsequently be
dissipated. The efficiency of this process is set mainly by the fraction
of the cluster volume filled by (sub-) kiloparsec-scale filaments and
bubbles of relativistic plasma.